Indiana's Complicated History With Time Zones

For most of the 20th century, Indiana counties made their own individual decisions about daylight saving time, resulting in a patchwork where neighboring counties — sometimes neighboring towns — could be on different clocks for parts of the year.

Indiana didn't adopt statewide daylight saving observance until 2006, making it the most recent state to fully standardize its DST practice. Before that, most of the state stayed on standard Eastern Time year-round while a few counties near Chicago and Evansville observed Central Time with daylight saving.

Indiana still splits between two zones: most of the state, including Indianapolis, is on Eastern Time, while the northwest corner near Chicago and the southwest corner around Evansville are on Central Time. What changed in 2006 was that all Indiana counties began observing daylight saving consistently, not that the zone split itself went away.

Business groups, particularly in Indianapolis, argued for years that the lack of statewide daylight saving cost the state economically by complicating scheduling with neighboring states that did observe it, and by creating confusion for national companies trying to coordinate meetings and shipments with Indiana offices.

The Indiana General Assembly passed the law adopting statewide daylight saving in 2005, and it took effect the following year, ending nearly four decades where Indiana's relationship to its neighbors' clocks shifted twice a year in an unusually inconsistent way.

The 2006 change also settled a long-running practical annoyance: airline schedules, TV broadcast listings, and interstate business hours had to carry special Indiana exceptions for decades, since standard formulas for converting between US zones simply didn't work for a state that didn't follow the usual daylight saving pattern.

Indiana's remaining Eastern/Central split is far from unique — it's one of fourteen US states with an internal zone boundary — but Indiana's history stands out because the more disruptive issue for so long wasn't which zone a county was in, it was whether the county observed daylight saving at all.

That distinction is worth remembering when comparing Indiana to other split states: Kentucky, Tennessee, and Michigan have always had consistent DST observance on both sides of their internal splits, while Indiana's pre-2006 patchwork was unusual precisely because it combined a zone split with an observance split.